A high energy study of Lyman alpha radiation for the interaction of tritium ion, deuterium ion, and hydrogen ion with the atmospheric gases.

Abstract

Since the first experimental evidence that the external source of charged particles precipitating into the earth's atmosphere, resulting in the aurora, consisted of protons as well as electrons there has been great interest in the proton interaction processes that occur due to the collision of protons with the atmospheric gases. Though the distribution of the proton flux is typically weighted towards lower energies, from 10 to 50 keV, at times anywhere from 40 to 100% of the flux can consist of high-energy protons far in excess of 100 keV. Determining the interaction cross-sections for these high-energy events is important if a thorough analysis of the auroral mechanisms is to be made. Measurements of the L(α) emission cross-sections for the interaction of H₃⁺, H₂⁺, and H⁺ with N₂ and O₂ have been completed over the energy range from 140 to 603 keV. Results show monotonically decreasing L(α) cross-sections with increasing energy for the interaction of both species of hydrogen molecular ions and protons with N₂ and O₂ up to a cut-off, after which the cross-sections appear to be constant and independent of energy. This "plateau region" would seem to indicate a fairly abrupt change in the type or kind of process or processes that are occurring. By measuring the L(α) emission at a distance of 4 cm into the interaction region a type or kind of process or processes that are occurring. By measuring the L(α) emission at a distance of 4 cm into the interaction region a fraction of the cascade contributions were measured. However, at the high-energies used in these experiments that fraction is exceedingly small, comprising at most a few percent, even at the lowest experimental energy of 140 keV.